U.S. Pat. No. 4,275,101 discloses a fractionated and purified methyl alkyl siloxane useful as a lubricant for a high-density information disc. This lubricant has the formula ##STR1## wherein R.sub.1 and R.sub.2 are alkyl groups of 4-20 carbon atoms, x is an integer of 2-4, y is an integer of 0-2 and wherein the sum of x and y is 4 or less. This material can be purified by molecular distillation between 100.degree.-205.degree. C. The lubricant acts to reduce friction between the disc and a playback stylus and to improve the life of the disc. However, the discs are sensitive to moisture and on playback are subject to a phenomenon dubbed "carrier distress" which interferes with playback.
One way that has been found to reduce carrier distress is to wash the surface of the discs after molding to remove the surface salts and stains that form on the disc surface during the molding process. These salts are water-soluble and thus form non-homogeneous salt deposits after exposure to high relative humidity. Of course this cleaning process requires an additional step during manufacture.
In an effort to reduce the carrier distress, lubricant additives have also been tried. U.S. Pat. No. 4,355,062 discloses bis(hydroxyalkyl)disiloxanes useful as additives for the methyl alkyl siloxane lubricants which reduces carrier distress, particularly after high-temperature, high-relative-humidity stressing. A preferred dopant has the formula ##STR2## While very effective this additive is also very expensive.
Other lubricant additives are known for the methyl ethyl siloxane lubricants; however, some of them, such as hydroxylated amines disclosed in U.S. Pat. No. 4,330,583, have the disadvantage that the additives are not soluble in the lubricant and thus must be applied to the surface of the disc from separate solutions. Other known additives are insoluble, or not commercially available, or have other drawbacks.
In addition to the phenomenon known as carrier distress, other defects in the records cause skips during playback which is apparent to the viewer as blackouts, chatter and the like and thus are very annoying. The skips are probably due to the presence of dust particles or other debris that settles on the lubricated disc surface, adhering to the surface and causing the playback stylus to lift out of the information track. Thus the search for suitable lubricant additives has continued to find a lubricant additive that can provide both good carrier-distress performance and reduced skips.